| 摘要 |
PURPOSE:To improve blast efficiency by forming vanes one end of each of which is projected downward beyond the bottom of a hub, on the side face of said hub which is formed into a trapezoid having air vent on its top plate while the bottom of which is opened. CONSTITUTION:A mixed flow impeller 5 consists of vanes 5a and a hub 5b, and air vents 5c are formed on the top plate of the hub 5b. One end of each of the vanes 5a is projected beyond the bottom of the hub. Thereby, the interval between the bottom of the hub and the back plate of a casing is increased, causing the position where the direction of flow is changed to the radial direction to be in a zone lower than the bottom of the hub, and the generation of a turbulent zone ranging from near the bottom of the hub to the back plate of casing can be restrained, leading to improvement in efficiency.
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